Ventilator



March 27, 1956 B. E. CURRAN VENTILATOR 2 Sheets-Sheet 1 Filed Feb. 14 1955 rfi NVENTOR. @rnd/fc! E. Curran BYJASifwa/Vc/w@ March 27, 1956 B. E. cuRRAN 2,739,520

VENTILATOR Filed Feb. 14 1955 2 sheets-sheet 2 IN VEN TOR. -Zemard E. Curran 14 TTG/WYE Y United VENTILATOR Application February 14, 1955, Serial No. 487,732

1 Claim. (Cl. 98-84) This invention relates to a ventilator.

The invention has for an object to provide a novel and superior natural draft ventilator adapted to be mounted on the roof of a building or other structure from which it is desired to exhaust air, which may be economically manufactured, and in which the elements of the Ventilator are scientifically proportioned as to size and in predetermined relation to one another and to the cross sectional area of the eduction pipe so as to combine the highest overall level of performance with a maximum compactness of design and which may be constructed with minimum expenditure of labor and materials.

Another object of the invention is to provide a novel and improved ventilator of the character specified wherein the various elements comprising the ventilator are proportioned so as to enable certain of them to be compactly nested within one of the elements to form a rigid and drum-like package for shipment.

With these general objects in view and such others as may hereinafter appear the invention consists in the ventilator hereinafter described and particularly defined in the claim at the end of this specification.

ln the drawings illustrating the preferred embodiment of the invention:

Fig. l is a longitudinal cross sectional view of a round type ventilator embodying the present invention;

Fig. 2 is a plan view of the same;

Fig. 3 is a cross sectional exploded view of the various units of the ventilator;

Fig. 4 is a cross sectional view of the units shown in Fig. 3 assembled in nested relation within one of the elements; and i Fig. 5 is a cross sectional detail view of a modified form of an assembled unit, to be described.

In general in its preferred form the present invention contemplates a novel and improved natural draft ventilator having an eduction pipe, a suction band, a cap, an external louver and a wind baflie, and in which the size of the elements and the relative spacing of the same are proportioned with respect to one another and to the cross sectional area of the eduction pipe and in accordance with a predetermined formula, thereby producing a ventilator structure wherein are combined the highest overall level of performance, maximum compactness of design and which may be manufactured with minimum expenditure of labor and materials.

The various limiting proportions as to size and relative spacing of the elements are herein expressed in area percentages of the cross sectional area of the eduction pipe and have been determined after exhaustive performance tests to produce a ventilator capable of optimum performance in a design of maximum compactness and minimum expenditure of labor and materials.

'Referring now to the drawings, the round type ventilator herein illustrated includes a cylindrical eduction pipe 10, a cylindrical suction band 12 mounted on the eduction` pipe, a peaked cap 14 disposed a substantial tes Patent i ice 2 distance above and covering the mouth of the eduction pipe, an annular external louver 16 mounted between the upper portion of the suction band and the cap, and an annular wind baille 18 mounted between the eduction pipe and the lower portion of the suction band.

As herein illustrated, in the preferred form of the invention the lower edge of the suction band 12 is arranged substantially in the horizontal plane of thev mouth of the eduction pipe, and the annular wind-baffle 18 disposed between the pipe and the suction band is preferably provided with a wall angle of 30 from the horizontal with the outer edge of the bale extending above the horizontal plane of the lower edge of the suction band, and with the inner edge of the bale extending below such horizontal plane. The slope of the peaked cap may be varied within reasonable limits so long as it continues to serve as an umbrella for protecting the mouth of the eduction pipe, and preferably the cap is one having a wall angle of 25 from the horizontal and is preferably mounted with the top thereof extended above the plane of the upper edge of the suction band. The annular louver disposed between the cap and the suction band is preferably extended at a wall angle of about 45 more or less from the horizontal and is preferably disposed with the top edge thereof below the top of the cap and above the upper edge of the suction band, and with the lower edge of the louver disposed above the lower edge of the cap. As herein shown, the outside diameter of the cap may and preferably will be substantially equal to the inside diameter of the louver. The various elements may be connected in the desired spaced relation in any usual or preferred manner, herein shown as being connected by angle brackets, the cap member 14 being connected by angle brackets Ztl extending from the underside of the cap to the inner wall of the suction band 12, and the louver 16 being connected by angle brackets 22 extending between the brackets 20 and the inner Wall of the louver. The eduction pipe 10 may be connected to the inner wall of the suction band by angle brackets 24 which may cooperate with angle brackets 26 attached to and extended from the inner wall of the suction band. The wind baffle 1S may be directly connected to the angle brackets 24, as shown. The various brackets may be attached to their connecting elements in any usual or preferred manner, such as by bolts or by welding.

In a modified form of the invention, as shown in Fig. 5, the cap 14 may be secured to the louver 16 by a U-shaped bracket 23 extending from the underside of the cap to the inner wall of the louver, and the connected unit may be attached to the inner wall of the suction band by a second U-shaped bracket 30 extending from the outer wall of the louver to the inner wall of the suction band, as shown.

After extensive research and tests it has been found that a compact, highly efficient natural draft ventilator embodying the present invention may be produced embodying an eduction pipe, a suction band, a cap, an external louver between the cap and the upper portion of the suction band and a wind baftle partially closing the space between the lower portion of the suction band and the eduction pipe. It has been determined that the cap should be spaced vertically above the mouth of the eduction pipe so that the theoretical cylindrical surface which would be formed by the extension of the eduction pipe upwardly until it meets the horizontal plane passing through the lower edge of the cap has a surface area between l5() to 200% of the cross sectional area of the mouth of the eduction pipe, and for best results it is preferred that this spacing should be such that such cylindrical surface should have an area of about of the cross sectional area of the eduction pipe. It has also been determined that the projected area of the cap should be about 185% of the cross sectional area of the mouth of the eduction pipe with a permissible variation of plus or minus This relationship affords protection from rain fall. up to angles of about -25 from the vertical.

It has been further determined that the suction band should be of a cross sectional area of from 350 to 360% of the sectional area of the mouth of the eduction pipe and that the total effective area of exhaust consisting of the entire cross sectional area of the suction band at the top plus the net annular area between the suction band and the wind baffle and measured in the horizontal plane of the lower end of the suction band approximates something close to 500% of the cross sectional area of the eduction pipe. Experimental data has demonstrated that satisfactory results may be obtained within variations of these iigures of plus or minus 50%.

The wind baiile 18 partially closes the space between the bottom of the suction band and the eduction pipe in the manner illustrated in Fig. l of the drawings and provides a clearance 19 adjacent the lower edge of the suction band, and the amount of clearance has been determined to be about 110% of the cross sectional area of the mouth of the eduction pipe with a permissible variation of about plus or minus 20%. It has also been determined that the clearance between the edge of the cap and the suction band combined with the clearance between the wind bate and the lower edge of the suction band should be approximately 300% of the cross sectional area of the eduction pipe with a permissible variation of about plus or minus 35%,

In order to shield the mouth of the eduction pipe from precipitation at angles in excess of 20 to 25% while at the same time to provide minimum obstruction to the suction producing flow pattern of the air, the external louver 16 disposed between the cap and the suction band is preferably spaced from the cap so that the theoretical cylindrical surface passing through the inner upper edge of the louver and the lower peripheral edge of the cap has an area of about 128% of the cross sectional area of the eduction pipe. The annular clearance area between the lower peripheral edge of the louver and the surrounding adjacent portion of the suction pipe in the preferred form of the invention amounts to about 75% of the cross sectional area of the eduction pipe. It will be observed that the arrangement of the louver 16 together with the cap 14 and the upper edge of the suction band is such as to prevent precipitation from entering the mouth of the eduction pipe at any angle, and that the wind baille 1S, with its inner edge below thc mouth of the pipe and its outer edge above the lower edge of the suction band is positioned so as to prevent entry of the weather from the bottom under the influence of wind blowing up the slope of a roof. It will also be observed that the arrangement of the cap, louver and upper edge of the suction band relative to the wind baille is such as to reduce to a minimum the spatter area of the wind baie whereby to minimize the liability of moisture in the form of a vapor or mist from being deilected over the mouth of the eduction pipe. l

Provision is also made in the preferred embodiment of the invention for minimizing head loss due to the combined effect of turbulence and wall friction by proportioning the elements of the ventilator in a manner such as to permit the ilow of air from the eduction pipe through the ventilator to gradually and continuously expand as it progresses. tion this is accomplished by providing an orderly progression of clearance spaces. Thus, the space between the mouth of the eduction pipe and the cap measured by the theoretical cylindrical surface area between said mouth and the horizontal plane of the lower edge of the cap (175%) is increased as the air flow progresses to a cylindrical surface area of 233% of the eduction pipe area.

As measured by a vertical theoretical cylindrical surface passing through the periphery' of the cap at the lower edge thereof the permissible variation amounts to from about l5 to 20%. As the air flow progresses it is permitted to expand further by an increase in a theoretical cylindrical surface which extends vertically through the upper end of the wind baffle, and this area amounts to about 244% of the area of the eduction pipe with an allowable variation depending upon the clearances on either side of such surface in the path of liow of the air. Y

From the description thus far it will be observed that the preferred relationship between the various essential elements of the ventilator, as above described, insures maximum efficiency with minimum labor and materials. The results have been arrived at after extensive research, and the indicated permissible variations are such as to insure substantially peak performance while utilizing labor and materials to an extent which will insure economical manufacturing costs.

Referring now to Figs. 3 and 4, it will be observed that the present ventilator is preferably prefabricated in three separate sub-assemblies comprising an upper sub-assembly including the cap 14 and louver 16 connected by brackets 20, 22; an intermediate sub-assembly including the suction band 12 provided with the brackets 26; and a lower subassembly including the eduction pipe 10 and wind bathe 18. In the illustrated embodiment of the invention the suction band 12 is inverted and the upper sub-assembly may be inserted into the underside of the inverted suction band with the undersurfaces of the brackets 20 substantially flush with the lower edge of the inverted suction band, and with the turned up outer ends of the brackets 20 fitted snugly against the inner wall of the suction band. The lower sub-assembly may then be inserted into the upper end of the inverted suction band with the upper surfaces of the brackets 24 substantially flush with the upper edge of the suction band, and with the turned down outer ends of the brackets 24 tted snugly against the In the illustrated embodiment of the inveninner wall of the suction band. When thus arranged it will be observed that the outer ends of the brackets 24 engage the brackets 26 of the suction band, and the lower end of the eduction pipe 10 its over a portion of the conical surface of the peaked cap member 14. As thus arranged, the upper and lower sub-assemblies are snugly nested within the suction band to form a compact and rigid drum-like package which may be readily cartonized or crated for shipment.

In order to provide for the satisfactory drainage of any moisture which may nd its way within the ventilator by passage through the clearances between the suction band 12 and the outer edges of the louver 16, the cap 14 and the wind baille 18, it is preferred to space the inner edge of the wind bal'le 18 a short distance from the eduction pipe 10 to provide an annular clearance 19 through which this moisture may drain.

In the drawings and claims the cross sectional area of the eduction pipe is indicated as A, and the size and spacing of the remaining elements are expressed in terms of proportions relative to A.

While the preferred embodiment of the invention has been herein illustrated and described it will be understood that the invention may be embodied in other forms within the scope of the following claim.

Having thus described the invention, what is claimed is:

A ventilator comprising the following elements: an eduction pipe a suction band mounted on the eduction pipe, a cap conical having its lower edge extending outwardly of the periphery of the eduction pipe disposed a substantial distance above and covering the mouth of the eduction pipe, an annular external louver mounted between the upper portion of the suction band and the cap, and an annular wind baffle mounted between the eduction pipe and the lower portion of the suction band and spaced from the latter, the aforesaid elements of the ventilator being spaced and related to one another to impart to the ventilator high overall perfomance and to enable the production of the ventilator with minimum material and labor expense and in accordance with the following relationship: assuming the cross sectional area of the eduction pipe to be A square inches, the cross sectional area of the suction band lies within the range of from 350 to 360% of A plus or minus 50%, the cap is spaced above the mouth of the eduction pipe so that the theoretical cylindrical surface which would be formed by the extension of the eduction pipe upwardly until it meets the horizontal plane passing through the lower edge of the cap has a surface area of between 150 and 200% of A and the projected area of the cap is about 185% of A plus or minus 10%; that the clearance between the lower edge of the suction band and the annular wind baille is about 110% of A plus or minus 20%; that the clearance between the edge of the cap and the suction band combined with the clearance between the wind baie and the lower edge of the suction band is about 300% of A plus or minus that the external louver is disposed a distance above the lower edge of the cap so that the theoretical cylindrical surface passing through the inner upper edge of the louver and the lower peripheral edge of the cap has an area of about 128% of A and that the annular clear ance between the lower peripheral edge of the louver and the suction band should be about of A.

References Cited in the le of this patent UNITED STATES PATENTS 1,509,848 Silver Sept. 30, 1924 1.570,441 Jardine Jan. 19, 1926 1,783,406 Cibulas Dec. 2, 1930 2,127,100 Whitaker Aug. 16, 1938 2,376,642 Waterman et al May 22, 1945 

